Crystallizing of sugars



n ta es mfl No Draw-ing. Application April 3, 1957 Serial No. 650,302 I7 Claims; ci; 127 -58)" y invention isdirecte'd to improvements in thecrystallization'ofsu'gars. I

In the usual process of crystallizing' beet sugar (the process may varysomewhat in the case of crystallizing cane sugar "and corn sugar)thesugarliquors' (at certain stages called the filmass), which comprisethe sugar proper andthe molasses and various other impurities from whichthe sugar is to be separated by crystallization, and hereafter referredto as the syrup for convenience, are passed through so-calledcrystallizers, raw vacuum pans and intermediate pans where variousheating and evaporation procedures are elfected until ultimatelycrystalline sugar and molasses are obtained, the latter commonly beingpumped into storage or shipping tanks.

I have found that if there is admixed with the syrup small proportionsof certain compounds, hereafter de scribed, prior to effectingcrystallization of the sugar, various important advantages are obtained.One of these advantages is an increase in the percent of crystallizationor, in other words, an increase in the yield of the crystalline sugar,and the purity thereof. Another advantage is improvement of spinningperformance in the centrifuge. A further advantage is the reduction inthe amount of entrained air in the separated molasses and the purity ofthe molasses.

The compounds the utilization of which in the environment to which myinvention relates are fatty acid esters of glycosides, the fatty acidacyl radicals of which contain from 8 to 22 carbon atoms and especiallyfrom 12 to 14 carbon atoms. Of particular utility are the fatty aciddi-esters of methyl glueoside, especially those in which the fatty acidacyl radical contains predominately from 12 to 14 carbon atoms as may bederived, for instance, from coconut oil, coconut oil mixed fatty acidsor, fractions thereof containing mainly lauric or lauric and myristicacids. These glycoside esters are fully disclosed and methods for theirpreparation described in United States Letters Patent Nos. 2,759,922 and2,759,923, both patented August 21, 1956.

The glycoside esters may be added at any one or more stages of theprocess as, for instance, in the raw vacuum pans, when charged, or inthe intermediate pans when charged, or in the crystallizer when thelatter is charged, or in whole or in part at any of said stages or otherstages. For best results, the glycoside esters should be thoroughly orintimately mixed with the syrup. It is particularly desirable,therefore, that the glycoside esters be intimately admixed with thesyrup directly when the latter is charged to the raw vacuum pans sincethis results in an enhancement of the intimacy of admixture due to thelonger agitation during the various stages up to and including thecrystallization of the sugar.- From the intermediate pans a part of theglycoside esters goes forward with the sugar but, generally, passes onto the raws and then to the molasses.

The proportions of the glycoside esters utilized are variable althoughalways on the small side. Thus, for instance, good results are obtainedby adding to 20 Z pounds of coconut oil mixed fatty acid di-estersof.methyl glucos'ide to the crystallizer in a beet sugar operation when60,000 pounds of'syrup are=charged to said crystah lizer; or by adding10 to 20 pounds of said esterstothe raw vacuum pans when the latter arecharged with 60,000 poundsof syrup; or by adding 10 to 20 pounds of saidesters to the raw pans-when chargedwith 60,000 pounds of syrup and byadding 8 to 12 pounds of said esters when the syrup is charged to theintermediate pans; or by adding '8 to 12 pounds of said esters to theintermediate pans when the latter are chargedwith 60,000. pounds ofsyrup from the raw vacuum pans. It will be understood that theseproportions are merely illustrative. The amounts are variable, asindicated, and will depend, in part, on the particular glycoside estersor mixtures thereof utilized, upon the extent to which optimum resultsare sought, upon theparticular stage. at which the glycoside esters areadded in the process, and upon the particular type of sugar beingcrystallized, Thus, for-instance, in general, greater percentages areused with corn sugar than with beet sugar. In general, the proportionsof glycoside est rs will range from as low as about 0.01% .to as high asabout"2%, and preferably from 0.03% to 1.5%, by

weight of the charge.

In actual tests on a plant scale, the percent of crystallization of beetsugar without the practice of my invention amounted to 58.5% whereas, bythe practice of my invention, in the manner described above, the percentof crystallization increased to 59.5% and higher. The increase in thepercent of crystallization may vary from of the order of 0.5% to as muchas 3% or 4%, depending on the various factors discussed above. Thefollowing table is illustrative of various of plant scale tests in thecrystallization of beet sugar:

N 0. of Strikes Average in Determin- Percent Treatment (with coconut oilTest No. ing Percent Crystallizafatty acid di-ester of methylOrystallization glucoside) tion 13 58. 5 None. 30 59. 5 121; incrystallizer. 32 60. 8 12# in raw pans. 11 60.7 6# in intermediate and12# in raw pans. 9 61.4 8# lntntermediate pans. 14 60.3 None. 14 60. 68# in intermediate pans.

Over and above and independently of the advantage of increases in yieldsof sugar in the crystallization step, the use of the glycoside estersalso serves very effectively to reduce the entrainment of air in theby-product molasses. Air entrainment by the molasses is highlyobjection-- able because it causes the apparent density of the molassesto be lowered to a point where it is difficult to make minimum weightsfor tank car and tank truck shipments. It also causes pumpingdifliculties while filling storage tanks and emptying cars and reducesstorage capacity by as much as 30% to 40%. By the addition of theglycoside esters in accordance with my invention, this problem is veryeffectively overcome. The quality of the molasses is enhanced and aconsiderably more salable product is obtained. The improvement inmolasses quality in the aforesaid regards is greater at Brix values of82 to 83 than at Brix values of 84 and higher but in all cases ispronounced.

While the glycoside esters can be used as such in the practice of myinvention, it is within the scope of my invention to use the glycosideesters in the form of mixtures thereof with a carrier or diluent as, forinstance, triglyceride oils, notably vegetable oils such as cottonseedoil, corn oil, soya oil, etc., or mineral oils, or methyl esters oftriglyceride oil fatty acids. Furthermore said glycoside esters, as suchor admixed with said diluents or carriers, can be used in admixture withemulsifiers such as higher fatty acid monoglycerides, andpolyoxyethylene glycol esters of higher fatty acids such as polyethyleneglycol (400) mono-oleate, to obtain the known. added advantages of saidemulsifiers.

What I claim as new and desire to protect by Letter Patent of the UnitedStates is: I Y

1. In the process of crystallizing sugars, the step which comprisescarrying out the crystallization in the presence of a fatty acid esterof a glycoside, the fatty acid acyl radical of said ester containingfrom 8 to 22 carbon atoms.

. 2. In the process of crystallizing beet sugar, the step whichcomprises carrying out the crystallization in the presence of a fattyacid ester of a glycoside, the fatty acid acyl radical of said estercontaining from '8 to 22 carbon atoms. r

3. In the process of crystallizing sugars, the step which comprisescarrying out the crystallization in the presence of a fatty aciddi-ester of methyl glycoside, the fatty acid acyl radical containingfrom 8 to 22 carbon atoms.

4. In the process of crystallizing sugars, the step which comprisescarrying out the crystallization in the presence of a fatty aciddi-ester of methyl glucoside, the fatty acid acyl radical containingpredominately from 12 to 14 carbon atoms.

5. In the process of crystallizing sugars, the step which comprisesintimately admixing a sugar syrup, prior to crystallization of the sugartherefrom, with from 0.01% to -2%, by weight, of a fatty acid ester of aglycoside, the fatty acid acyl radical of'said ester containing from 8to 22 carbon atoms.

6. In the process of crystallizing beet sugar, the step which comprisesintimately admixing beet sugar syrup, prior to crystallization of thesugar therefrom, with from 0.3% to 1.5%, by weight, of a fatty aciddi-ester of methyl glucoside, the fatty acid acyl radical containingpredominately from 12 to 14 carbon atoms.

7. In the process of crystallizing corn sugar, the step which comprisesintimately admixing corn sugar syrup, prior to crystallization of thesugar therefrom, with from 0.3% to 2%, by weight, of a fatty aciddi-ester of methyl glycoside, the fatty acid acyl radical containingpredomi- 20 nately from :12 to 14 carbon atoms.

References Cited in the file of this patent UNITED STATES PATENTS700,099 Spreckels et al May 13, 1902 King Apr. '8, 1952

1. IN THE PROCESS OF CRYSTALLIZING SUGARS, THE STEP WHICH COMPRISESCARRYING OUT THE CRYSTALLIZATION IN THE PRESENCE OF A FATTY ACID ESTEROF A GLYCOSIDE, THE FATTY ACID ACYL RADICAL OF SAID ESTER CONTAININGFROM 8 TO 22 CARBON. ATOMS.